Exemplary embodiments relate to a voltage generation circuit and a nonvolatile memory device using the same, which are capable of improving the reliability of an operation in the operation of the circuit in which current consumption increases sharply/drastically.
In a known semiconductor circuit or a known memory device, current consumption may increase sharply in performing a specific operation, where such an increase raises a concern. For example, in a refresh operation of DRAM and a precharge operation of flash memory, current consumption can sharply increase. Such a sharp increase in current consumption during operations of a flash memory is described below as an example.
To write data into the memory cell of a flash memory device, a program operation is performed. The program operation is performed by supplying a program pulse to the memory cell according to an incremental step pulse program (ISPP) method, and a verification operation is performed for every pulse by checking whether the memory cell has been programmed.
If, as a result of the check, the memory cell has been programmed, the memory cell is treated as being a program pass. However, if, as a result of the check, the memory cell has not been programmed, a next program pulse is supplied to the memory cell.
Such a verification operation can be mainly divided into a bit line precharge period, an evaluation period, and a sense period. Here, in the bit line precharge period, a large current consumption occurs because the bit lines BL have to be precharged, and a voltage drop in a supply voltage occurs due to the large current consumption. Such a drop in the supply voltage affects the overall operation of the nonvolatile memory device including an internal clock of the nonvolatile memory device and raises a concern.
In the known bit line precharge period of a verification operation, a voltage is supplied to a sense unit configured to electrically couple a bit line and the precharge unit of a page buffer. A voltage level of the supplied voltage is determined based on the cut state of a fuse, where such a state is stored in an internal register. Thus, a voltage supply unit generates the voltage supplied to the page buffer through the sense unit. The voltage supply unit determines the voltage level of the voltage to be supplied to the page buffer in response to the cut state of the fuse. For example, when the cut state of a fuse is once determined, the voltage level of the voltage generated by the voltage supply unit in response thereto is determined. The voltage level of the supplied voltage, once determined, is not changed. Thus, a concern is raised with respect to the bit line precharge period in which current consumption sharply increases because a fixed voltage is to be continuously supplied as described above.